Etching method and etching apparatus

ABSTRACT

A technique improves pattern features formed by etching and the uniformity of the features across the surface of a substrate. An etching method includes steps a), b), c), d), and e). Step a) includes placing, on a support, a substrate including a target film. Step b) includes partially etching the target film and forming a recess. Step c) includes setting the temperature of the support at a first temperature, and forming, on a sidewall of the recess, a first film having a first film thickness distribution. Step d) includes partially further etching the target film having the first film formed on the target film. Step e) includes setting the temperature of the support at a second temperature different from the first temperature, and forming, on the sidewall of the recess, a second film having a second film thickness distribution different from the first film thickness distribution.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation application of U.S. application Ser.No. 16/953,369, filed on Nov. 20, 2020, which claims priority toJapanese Patent Application No. 2019-212241 filed on Nov. 25, 2019, theentire disclosure of each of which are incorporated herein by reference.

BACKGROUND Technical Field

The present disclosure relates to an etching method and an etchingapparatus.

Description of the Background

For semiconductor devices that are integrated further in the verticaldirection in addition to the horizontal direction, patterns are formedwith higher aspect ratios during their manufacturing processes. In 3DNAND manufacturing processes, for example, channel holes are formed in adirection through many metal wiring layers. For a 64-layer memory cell,channel holes are formed to provide an aspect ratio of as high as 45.

Various methods have been developed to accurately form patterns with ahigh aspect ratio. An example technique is to control the size of apattern formed by semiconductor etching at the nanometer scale (PatentLiterature 1). This technique uses a self-assembled monolayer (SAM) or afilm formed by atomic layer deposition (ALD) as a passivation layer, Thepassivation layer is formed on a sidewall of a recess in the substrate.The substrate, or the bottom of the recess, is then etched to achievehigh-accuracy anisotropic etching.

CITATION LIST Patent Literature

Patent Literature 1: U.S. Patent Application Publication No.2010/0173494

BRIEF SUMMARY

The present disclosure is directed to a technique for improving patternfeatures formed by etching or their uniformity across the surface of thesubstrate.

An etching method according to one aspect of the present disclosureincludes steps a), b), c), d), and e). Step a) includes placing, on asupport, a substrate including a target film. Step b) includes partiallyetching the target film and forming a recess. Step c) includes setting atemperature of the support at a first temperature, and forming, on asidewall of the recess, a first film having a first film thicknessdistribution. Step d) includes partially further etching the target filmhaving the first film formed on the target film. Step e) includessetting the temperature of the support at a second temperature differentfrom the first temperature, and forming, on the sidewall of the recess,a second film having a second film thickness distribution different fromthe first film thickness distribution.

The exemplary technique according to the present disclosure improvespattern features formed by etching or their uniformity across thesurface of the substrate.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a flowchart of an exemplary etching method according to afirst embodiment.

FIG. 2A is a diagram illustrating an exemplary pattern formed with theetching method according to the first embodiment.

FIG. 2B is another diagram illustrating an exemplary pattern formed withthe etching method according to the first embodiment.

FIG. 2C is another diagram illustrating an exemplary pattern formed withthe etching method according to the first embodiment.

FIG. 2D is another diagram illustrating an exemplary pattern formed withthe etching method according to the first embodiment.

FIG. 3A is a graph showing experimental results obtained under a firsttemperature condition.

FIG. 3B is a graph showing experimental results obtained under a secondtemperature condition.

FIG. 4 is a graph showing the experimental results of FIGS. 3A and 3Btogether.

FIG. 5 is a diagram showing exemplary conditions used with the etchingmethod according to the first embodiment.

FIG. 6 is a flowchart of an exemplary etching method according to asecond embodiment.

FIG. 7A is a diagram of a support having exemplary zones included in anetching apparatus according to the second embodiment.

FIG. 7B is a diagram of the support having other exemplary zonesincluded in the etching apparatus according to the second embodiment.

FIG. 7C is a diagram of the support having still other exemplary zonesincluded in the etching apparatus according to the second embodiment,

FIG. 8 is a diagram showing exemplary conditions used with the etchingmethod according to the second embodiment.

FIG. 9A is a diagram illustrating exemplary feature correction with theetching method according to the second embodiment.

FIG. 9B is a diagram illustrating other exemplary feature correctionwith the etching method according to the second embodiment.

FIG. 10 is a diagram of an exemplary etching apparatus according to oneembodiment.

DETAILED DESCRIPTION

Embodiments of the present disclosure will now be described withreference to the drawings. The present embodiments are not limiting.Additionally, the techniques described in the embodiments may becombined as appropriate, unless any contradiction arises in theprocessing. In the drawings, similar or corresponding components areindicated by like reference numerals. The embodiments are illustrated byway of example and not by way of limitation in the accompanying drawingsthat are not to scale unless otherwise indicated.

In the embodiments, a pattern formed on a substrate will be described byreferring to a direction substantially perpendicular to the substratesurface as either the thickness direction or the vertical direction. Adirection substantially parallel to the substrate surface is referred toas a lateral direction. For a substantially disk-shaped substrate, adirection from the disk center toward the circumference and parallel tothe substrate surface is also referred to as a radial direction.

A pattern herein refers to any features formed on the substrate. Thepattern collectively refers to holes, trenches, lines and spaces, masks,and any other features formed on the substrate. A recess in the patternon the substrate refers to a portion recessed in the thickness directionof the substrate. A recess includes a sidewall defining its innerperiphery, a bottom portion defining the bottom, and a top continuouswith the sidewall and defining a substrate surface portion near thesidewall. Additionally, a space defined by the edge of the top isreferred to as an opening. The term opening is also used to refer to theentire space surrounded by the bottom and the sidewall of the recess, orto any position of the space.

Feature Failures in Semiconductor Processes

Etching for forming a pattern with a high aspect ratio can involvefeature failures. For example, a recess to be formed in the verticaldirection (film thickness direction) can have an inner peripheryexpanding in the lateral direction, thus having feature failures. Suchfeature failures are called bowing.

Bowing often occurs directly below the interface between different typesof films formed on a substrate. The etching rate differs between, forexample, a target film to be etched and a layer serving as a mask foretching stacked on the target film. A portion of the target film thatmeets the mask is etched more, thus forming an opening that expands inthe lateral direction directly below the mask.

Bowing may also occur near the bottom of the recess in the substrate.This n ay result from excessive etching of the sidewall with ionsbouncing and colliding against the sidewall of the recess through, forexample, a distorted mask.

In addition to bowing, the pattern may taper in the depth direction.This can occur seemingly because less etchant reaches a deeper portionof the pattern. To reduce such feature failures, a protective film is tobe formed at a controlled position with a controlled thickness.Flowchart of Exemplary Etching Method according to First Embodiment

FIG. 1 is a flowchart of an exemplary etching method according to afirst embodiment. With the etching method according to the firstembodiment, at least one of the position or the thickness of a filmformed on a substrate is controlled by controlling the temperature of asupport onto which the substrate is placed.

First, a substrate is provided (step S100). For example, the substrateincluding a target film and a mask on the target film is provided. Thesubstrate is loaded into a reaction chamber accommodating the support,and is placed onto the support. The substrate placed on the supportundergoes multiple cycles of processing. In FIG. 1, n indicates thenumber of processing cycles, and n is 1 at the start of the processing.

The target film is partially etched (step S101). This partial etchingforms a pattern including a recess in the substrate. In step S101, anetching gas is supplied into the reaction chamber and plasma isgenerated. Ions contained in the plasma are drawn into the target film,thus etching the film.

This is followed by controlling the temperature of the substrate and thetemperature of the support onto which the substrate is placed at an n-thtemperature (for the first cycle, the first temperature) to form an n-thfilm on the recess (step S102). The n-th film has an n-th film thicknessdistribution corresponding to the n-th temperature. During the firstcycle of film deposition, for example, the temperature of the support iscontrolled at the first temperature. A first film having a first filmthickness distribution is then formed. The target film having the firstfilm on it is partially further etched (step S103).

This is then followed by determining whether the processing countreaches a predetermined number (step S104). When the processing countreaches the predetermined number (Yes in step S104), the processingends. When the processing count has not reached the predetermined number(No in step S104), the processing count is updated (n=n+1 in step S105),and the processing returns to step S102. When, for example, thepredetermined number is 10 and the processing count is 1, the processingreturns to step S102, in which the second cycle of film deposition isperformed. During the second cycle of film deposition, in step S102, thesupport is controlled at the second temperature, and a second filmhaving a second film thickness distribution is formed.

The processing is thereafter repeated until the processing count reachesthe predetermined number. Once the processing count reaches thepredetermined number, the processing ends.

In the processing shown in FIG. 1, a single cycle of processing mayinclude processes other than the film deposition (step S102) and theetching (step S103). For example, the single cycle of processing mayinclude, in addition to the etching in step S103, another etchingprocess under a processing condition different from the condition usedin step S103. For example, the single cycle of processing may include,in addition to the film deposition in step S102, another film depositionprocess under a processing condition different from the condition usedin step S102. The etching in step S103 and the film deposition in stepS102 may each include one or more steps. In step S103, for example, anetching process may be performed multiple times under the same ordifferent processing conditions. In step S102, a film deposition processmay be performed multiple times under the same or different processingconditions.

In the example shown in FIG. 1, the processing count is preset. In someembodiments, the pattern features may be measured after the filmdeposition in step S102, and the measurement results may be used todetermine whether to perform the next processing and also to determinethe temperature of the support. The processing count may be preset bycalculating the number of times the etching process is to be performedto reach a desired etching depth (step S103).

Exemplary Pattern Formation in Embodiment

FIGS. 2A to 2D are diagrams each illustrating an exemplary patternformed with an etching method according to one embodiment.

The film deposition in step S102 of FIG. 1 uses, for example,unsaturated atomic layer deposition (ALD), which is also calledsub-conformal ALD. Before the pattern formation is described withreference to FIGS. 2A to 2D, ALD will now be described.

ALD usually includes four steps. A first reactant (also referred to as aprecursor) is first introduced into the reaction chamber accommodatingthe substrate. A first material contained in the first reactant isadsorbed on the surface of the substrate. After the surface is coveredwith the first material, the reaction chamber is evacuated.Subsequently, a second reactant (also referred to as a reaction gas)containing a second material that reacts with the first material isintroduced into the reaction chamber. The second material reacts withthe first material on the substrate to form a film. The reaction of thesecond material with the first material on the surface ends to completethe film deposition. In ALD, predetermined materials are adsorbed on andreact with substances present on the substrate surface in aself-limiting manner, thus forming films. Providing a sufficientprocessing duration typically allows ALD to achieve conformal filmdeposition.

In contrast, unsaturated ALD uses a processing condition under whichmaterials are not completely adsorbed on or do not completely react witha substrate surface in a self-limiting manner. The processing can be inat least two modes described below.

-   (1) A precursor is adsorbed on the entire surface of the substrate.    A reactant introduced thereafter is regulated from spreading over    the entire surface of the substrate.-   (2) A precursor is adsorbed only on a part of the surface of the    substrate. A reactant introduced thereafter is deposited only on the    part of the surface having precursor adsorbed on it.

The etching method according to the first embodiment uses the technique(I) to control the position and the thickness of a film formed on asidewall of a recess.

FIG. 2A is a diagram illustrating a recess 200 in a first layer 101 on asubstrate 100 and a second layer 102 on top of the first layer 101formed through partial etching in step S101. In the example of FIG. 2A,the first layer 101 is a target film. The second layer 102 serves as amask in etching the first layer 101. The recess 200 has a bottom 200B, asidewall 2005, and a top 200T.

In FIG. 2A, the recess 200 gradually tapers from the lower end of thesecond layer 102 toward the bottom. In the state in FIG. 2A, furtheretching can proceed in the lateral direction and cause bowing. To reducesuch boning caused by etching, a protective film is formed, usingunsaturated ALD, on the sidewall of the recess 200 partially etched inthe first embodiment.

A precursor P is first introduced into a reaction chamber accommodatinga substrate, Providing a sufficient processing duration allows theprecursor P to adsorb on the entire surface of the substrate (FIG. 2B).The adsorption of the precursor P may or may not involve plasmageneration containing the precursor P. Once the precursor P is adsorbed,the gas in the reaction chamber is purged. A reactant R is thenintroduced into the reaction chamber, and undergoes a reaction with theprecursor P adsorbed on the substrate surface. The reaction of thereactant R with the precursor P may be performed using a reaction gascontaining the reactant R introduced into the reaction chamber, or usingplasma generated with the reactant R to react with the precursor P (FIG.2C). The introduced reactant R then reacts with the precursor P on thesubstrate, thus gradually forming a protective film 300 (refer to FIG.2D) from above the second layer 102. Before the protective film 300forms on the bottom 200B of the recess 200. the reactant R is purgedfrom the reaction chamber. With this process, the protective film 300can form simply on the upper portion of the first layer 101 and on thesecond layer 102 with the ALD method (FIG. 2C), rather than on theentire sidewall 200S of the recess 200. Repeating the processes shown inFIGS. 2A, 2B, and 2C yields the features shown in FIG. 2D.

In the example of FIGS. 2A to 2D, the reactant R is regulated fromreaching the bottom 200B of the recess 200 to achieve unsaturated ALD.In another embodiment, the precursor P may be regulated from reachingthe bottom 200B of the recess 200 (the precursor P may be regulated fromadsorbing on the bottom 200B of the recess 200) to achieve unsaturatedALD.

Processing Conditions for Selective Adsorption and Reaction

With the etching method according to the first embodiment, as describedabove, the processing conditions are adjusted to allow a precursor toadsorb on or a reactant to react on a predetermined portion of apattern. In one embodiment, the processing conditions are adjusted toallow the precursor to adsorb only on and the reactant to react only onthe top and the upper portion of the sidewall of the recess.

The processing conditions adjustable for the etching method describedabove include the temperature of the support onto which the substrate isplaced, the pressure in the reaction chamber, the flow rate and theintroduction duration of the precursor, the flow rate and theintroduction duration of the reactant, and the processing duration ateach step. For the processing using plasma, the value of radio-frequency(RF) power applied to generate plasma may be adjusted.

The method in this example uses the temperature of the support tocontrol the position and the thickness of a film to be formed. AdjustingFilm Thickness and Film Deposition Position through Temperature Control

FIG. 3A is a graph showing experimental results obtained under a firsttemperature condition. FIG. 3B is a graph showing experimental resultsobtained under a second temperature condition,

in the experiments shown in FIGS. 3A and 3B, the processing involvingfour steps, or introducing a precursor, purging, introducing a reactant,and purging, was performed in 35 cycles. To introduce the reactant,plasma formed from the reactant was used. The precursor was asilicon-containing gas. The reactant was an oxygen gas diluted withargon. A silicon oxide film was formed as the protective film. In theseexperiments, the support was set at two different temperatures when thereactant was introduced. The thickness and the position of the filmformed were measured. The support was adjusted to the temperature of 10°C. in the experiment of FIG. 3A, and to the temperature of 60° C. in theexperiment of FIG. 3B. The introduction duration of the reactant(generation duration of plasma) was set to four values: one second, fourseconds, ten seconds, and the saturation completion duration (sufficienttime for the reactant to saturate completely on the substrate surface).

In FIGS. 3A and 3B, the horizontal axis indicates the size of theopening, or the critical dimension (CD) of the recess formed innanometers (nm), and the vertical axis indicates the depth of the recessin micrometers (pin). In the figures, the “initial” indicates the CD ofthe recess before the experiment was started, and the “conformal”indicates the CD when the processing was performed for the saturationcompletion duration. For conformal, films were formed with asubstantially uniform thickness irrespective of the depth of the recess,as shown in FIGS. 3A and 3B.

Subsequently, the thickness of each film formed using the reactant for adifferent introduction duration was measured. As shown in the graph ofFIG. 3A, the film formed using the reactant introduced for theintroduction duration of 10 seconds was substantially conformal,although its thickness slightly decreases downward. With the reactantintroduced for the introduction duration of 4 seconds, the resultantfilm has a thickness different from the film obtained for the reactantintroduction duration of 10 seconds, and is thinner in a lower portionof the sidewall of the recess than the film obtained for the reactantintroduction duration of 10 seconds. With the reactant introduced forthe introduction duration of one second, the film was formed with thethickness gradually decreasing downward from the top of the recess to adepth of about 0.6 μm, but almost no film was formed in the portionlower than the depth of 0.6 μm.

As shown in the graph of FIG. 3B with the support set at 60° C., thefilm formed with the reactant introduced for the introduction durationof 10 seconds was substantially conformal, although the thicknessslightly decreases downward. With the reactant for the introductionduration of 4 seconds, the resultant film has a thickness different fromthe film obtained for the reactant introduction duration of 10 seconds,and is thinner in a lower portion of the sidewall of the recess than thefilm obtained for the reactant introduction duration of 10 seconds. Withthe reactant introduced for the introduction duration of one second, thefilm was formed with the thickness gradually decreasing downward fromthe top of the recess to a depth of about 1 μm, but almost no film wasformed in the portion lower than the depth of 1 μm.

With the introduction duration set shorter, a film can be formed withthe thickness gradually decreasing in the film thickness direction of apattern in either case. In particular, when the introduction duration ofthe reactant was set for one second, controlling the temperature of thesupport at 10° C. can reduce film deposition at positions lower than thedepth of 0.6 μm, and controlling the temperature of the support at 60°C. can reduce film deposition at positions lower than the depth of 1 μm.As described above, the experiment results shown in FIGS. 3A and 3Breveal that changing the temperature of the support can adjust thethicknesses and the distributions of the resultant films.

FIG. 4 is a graph showing the experiment results of FIGS. 3A and 3Btogether. FIG. 4 specifically shows the experiment results combined onthe graph showing the correspondence between the saturation duration ofoxygen (O₂) plasma calculated using, for example, a diffusion equationand the aspect ratio.

As shown in FIG. 4, the lowermost position (A/R: aspect ratio) of thefilm formation varies in correspondence with changes in the introductionduration of the reactant (irradiation duration of O₂ plasma in thisexample). The lowermost position of the film formation differs by anaspect ratio of about 20 (portion indicated by the arrow in FIG. 4)between when the temperature of the support was set at 10° C. and whenthe temperature of the support was set at 60° C. Varying the temperatureof the support within a range of 10° C. to 60° C., for example, can varythe lowermost position of film deposition within the aspect ratio rangeof about 20.

The etching method according to the first embodiment includes estimatingthe positions of possible feature failures, such as bowing and tapering,and forming a protective film in an area of possible feature failures.The etching method according to the first embodiment also includesadjusting the film deposition area by adjusting the temperature of thesupport onto which the substrate is placed. Additionally, the etchingmethod according to the first embodiment may use unsaturated ALD to forma film with a thickness gradually decreasing in the film thicknessdirection. In the first embodiment, a protective film can be formed inan area or (or at positions) of possible feature failures, such astapering or bowing.

Example of Temperature Control

In FIG. 1, the setting temperature for the support was changed in theorder of the first temperature arid the second temperature in the filmdeposition (step S102) for ease of explanation. However, the settingtemperature for the support may be changed for every cycle of filmdeposition, or may be unchanged. The setting temperature for the supportmay be the same over multiple cycles of film deposition. In other words,the first temperature and the second temperature may be the same, or thefirst temperature may be higher or lower than the second temperature,depending on the feature of a recess to be formed or on the processingconditions.

To form a recess with less feature failures that tapers to have anarrower opening from the top toward the bottom, for example, aprotective film may be formed to have its film thickness decreasing fromthe top toward the bottom. The temperature of the support may beincreased in the protective film formation (step S102 in FIG. 1) inaccordance with an increase in the aspect ratio of the recess to formthe protective film in a more downward area.

To reduce bowing in an upper portion of the recess, for example, thetemperature of the support may be decreased in the protective filmformation. This forms the protective film that covers a portionsusceptible to bowing. To reduce bowing near the bottom of the recess,for example, the temperature of the support may be increased in theprotective film formation.

In this manner, identifying the positions of possible feature failuresand forming a. protective film as thick as to cover such failurepositions can improve the pattern features.

FIG. 5 is a diagram showing exemplary conditions used with the etchingmethod according to the first embodiment. The conditions used in theexample of FIG. 5 include the processing count, the support temperature,and the processing condition. The processing count refers to the numberof cycles of processing performed, or the ordinal number. The supporttemperature refers to the setting temperature for the support for thecorresponding cycle of film deposition step S102 in FIG. 1). Theprocessing condition refers to a processing condition other than thesupport temperature. The processing condition includes, for example, thetype of precursor, the type of reactant, the flow rate, and the pressurein the reaction chamber. In the example of FIG. 5, the support was setat 10° C. for the processing count of 1 to 10, at 20° C. for theprocessing count of 11 to 20, and at 30° C. for the processing count of21 to 30. Under the conditions shown in FIG. 5, the temperature of thesupport is increased as the processing proceeds to form a protectivefilm at positions gradually downward. The etching method according tothe first embodiment may use other temperature conditions. For example,the temperature of the support may be increased once and then decreasedas the processing proceeds, or the temperature of the support may bedecreased gradually.

Advantageous Effects of First Embodiment

The etching method according to the first embodiment includes steps a),b), c), d), and e). Step a) includes placing, on a support, a substrateincluding a target film. Step b) includes partially etching the targetfilm and forming a recess. Step c) includes setting the temperature ofthe support at a first temperature, and forming, on a sidewall of therecess, a first film having a first film thickness distribution. Step d)includes partially further etching the target film having the first filmformed on the target film. Step e) includes setting the temperature ofthe support at a second temperature different from the firsttemperature, and forming, on the sidewall of the recess, a second filmhaving a second film thickness distribution different from the firstfilm thickness distribution. The method according to the firstembodiment can form the first film having the first film thicknessdistribution corresponding to the first temperature and the second filmhaving the second film thickness distribution corresponding to thesecond temperature. The method according to the first embodiment canform a film with a film thickness distribution adjusted in accordancewith the temperature. This improves the pattern features formed bysemiconductor etching.

In the first embodiment, the first temperature differs from the secondtemperature,

The first temperature may be lower than the second temperature. Thefirst temperature may be higher than the second temperature. The methodaccording to the first embodiment adjusts the temperature to adjust thefilm thickness distribution in accordance with pattern features formedby semiconductor etching. The method according to the first embodimentcan form a protective film in an area of possible pattern featurefailures resulting from etching.

In the first embodiment, other processing conditions may be adjusted toadjust the film thickness distribution, in addition to or instead ofadjusting the temperature of the support. For example, step c) above mayinclude steps c-1)) and c-2). Step c-1) includes supplying a firstreactant and causing the first reactant to be adsorbed on the sidewallof the recess. Step c-2) includes supplying a second reactant andcausing the second reactant to react with the first reactant to form afilm. Step e) above may also include steps e-1) and e-2). Step e-1)includes supplying a third reactant and causing the third reactant to beadsorbed on the sidewall of the recess. Step e-2) includes supplying afourth reactant and causing the fourth reactant to react with the thirdreactant to form a film. Step c-2) may be performed for a processingduration different from a processing duration of e-2) to form the filmto have at least one of a thickness or a position different from athickness and a position of the film formed in e-2). Adjusting theprocessing conditions in this manner can thither improve the patternfeatures formed by semiconductor etching.

In the first embodiment, the first film thickness distribution refers tothe distribution of the film thicknesses varying across the thickness ofthe substrate. In the first embodiment.

adjusting the film thickness distribution in the thickness direction ofthe substrate can improve the pattern features formed by etching.

In the first embodiment, a target film is an etching target film insteps b) and d), and a mask be placed on top of the etching target film.The target film may be a silicon-containing film. The silicon-containingfilm may be a silicon-containing dielectric film. An example of thesilicon-containing dielectric film includes a silicon oxide film(SiO_(x)). The mask on the target film may include a carbon-containingmask or a metal-containing mask. The target film and the mask may besilicon-containing films having different compositions.

In the first embodiment, steps h), c), d), and e) may be repeated untilthe aspect ratio of the recess reaches at least 40. Thus, the aspectratio of the recess is adjustable in accordance with the type ofsemiconductor device to be manufactured or a process according to thefirst embodiment.

Second Embodiment

In the first embodiment, the setting temperature for the support ischanged for each cycle of film deposition to adjust the position and thethickness of a film to be formed. In some embodiments, the support mayhave varying temperatures across its surface. In a second embodiment, anexemplary method including film deposition at temperatures varyingacross the surface of the support will be described.

FIG. 6 is a flowchart of an exemplary etching method according to thesecond embodiment. First, a substrate is provided (step S200). Forexample, the substrate including a target film and a mask on the targetfilm is provided. The substrate is loaded into a reaction chamberaccommodating the support, and is placed onto the support. The substrateplaced on the support undergoes multiple cycles of processing. In FIG.6, n indicates the number of processing cycles, and n is 1 at the startof the processing. The processing in step S200 is the same as step S100shown in FIG. 1.

The target film is partially etched (partial etching in step S201) toform a pattern including a recess on the substrate.

This is followed by controlling the temperature of the substrate and thetemperature of the support onto which the substrate is placed. At leasttwo of multiple zones of the support are controlled to differenttemperatures, and films (protective films) are formed (step S202), Eachof the films has a different film thickness distribution correspondingto the control temperature of the corresponding zone of the support. Forexample, a first film formed in a first zone controlled at a relativelyhigh temperature has a first film thickness distribution different fromthe second film thickness distribution of a second film formed in asecond zone controlled at a relatively low temperature. For example, thelowermost position of the first film is lower than the lowermostposition of the second film. The target film with the first film and thesecond film is partially further etched (step S203).

This is then followed by determining whether the processing countreaches a predetermined number (step S204). When the processing countreaches the predetermined number (Yes in step S204), the processingends. The predetermined number is one or more. When the processing counthas not reached the predetermined number (No in step S204), theprocessing count is updated (n=n+1 in step S205), and the processingreturns to step S202 to perform film deposition. A set of temperaturesused for multiple zones of the support in the n +1-th cycle of filmdeposition may differ from a set of temperatures used in the n-th cycle.The set of temperatures herein refers to multiple temperatures used forthe respective zones.

The processing is thereafter repeated until the processing count reachesthe predetermined number. Once the processing count reaches thepredetermined number, the processing ends.

Zones with Controllable Temperatures

As described above, the support for each cycle of film deposition can beset to multiple temperatures in the second embodiment, rather than beingset to a single temperature. The multiple temperatures correspond to therespective zones of the support. The zones of the support will now bedescribed.

To vary the temperature of the support across its surface in the secondembodiment, the support surface may have multiple zones defined to allowindependent temperature control in each zone. The support accommodatesheaters for the respective zones.

The support may have any number of zones with any shapes defined forindependent temperature control. For example, a circular support surfacemay have multiple zones defined concentrically. Each zone may furtherhave multiple zones defined circumferentially. Each zone may have eitherthe same number of zones or a different number of zones definedcircumferentially. Each zone may have zones defined either atcircumferentially same positions or at circumferentially differentpositions.

FIGS. 7A to 7C are diagrams of exemplary zones in the support includedin an etching apparatus according to the second embodiment. In thesecond embodiment, the support may have multiple zones defined to allowindependent temperature control in each zone.

A support 11A shown in FIG. 7A has three zones. A first zone Z1corresponds to a. central portion of the substrate. A second zone Z2corresponds to an edge portion of the substrate. A third zone Z3corresponds to an annular portion between the central portion and theedge portion of the substrate. The first zone 71, the second zone Z2,and the third zone Z3 may have any sizes.

A support 11B shown in FIG. 7B has 14 zones. The support 11B has fourzones defined concentrically from the center toward the circumference. Acircular first zone Z1 is located at the center. The first zone Z1 issurrounded by the separate quarters of a doughnut shape, orspecifically, a second zone 72, a third zone Z3, a fourth zone Z4 and afifth zone Z5. The second to the fifth zones Z2 to 75 are furthersurrounded by eight zones. The eight zones are a sixth zone Z6, aseventh zone Z7, an eighth zone 78, a ninth zone Z9, a tenth zone Z10,an eleventh zone Z11, a twelfth zone Z12, and a thirteenth zone Z13. Thesixth to the thirteenth zones Z6 to Z13 are further surrounded by anannular fourteenth zone Z14.

A support 11C shown in FIG. 7C also has 14 zones. The support 11C hasfour zones defined radially, and further has zones definedcircumferentially. A first zone Z1 is a circular portion at the center.The annular portion surrounding the first zone Z1 has fourcircumferentially defined zones, which are a second zone Z2, a thirdzone Z3, a fourth zone Z4, and a fifth zone Z5. A sixth zone Z6, whichis the second outermost peripheral portion, does not havecircumferentially defined zones. The outermost peripheral portion haseight zones Z7 to Z14 defined circumferentially,

The zones of the supports shown in FIGS. 7A to 7C are mere examples. Thesupports may have other zones. The zones of the supports may correspondto the areas of the substrate. For example, a support may have a firstzone corresponding to a first area of the substrate and a second zonecorresponding to a second area of the substrate. In this case, the firstarea may include the center of the substrate, and the second area mayinclude the edge of the substrate.

Controlling the temperature of the support across the surface of thesupport will now be described with reference to FIG. 7A. The zones shownin FIG. 7A are appropriate for a. pattern that may vary between thecentral portion and the edge of the substrate. In film deposition andetching, for example, the film deposition amount and the etching amountmay van between the central portion and the edge portion of thesubstrate due to, for example, varying densities of plasma in theetching apparatus. In such a case, the support temperature is set low inareas with a larger film deposition amount and high in areas with asmaller film deposition amount.

FIG. 8 is a diagram showing exemplary conditions with the etching methodaccording to the second embodiment. The conditions illustrated in FIG. 8include the condition number, the support temperatures for the firstzone, the second zone, and the third zone, and the processingconditions. The condition number is a unique number for identifying eachset of conditions. The support temperatures refer to the temperatures ofthe respective zones of the support in the corresponding set ofconditions. The support temperatures can be different values for thefirst, second, and third zones. The processing conditions refer toprocessing conditions other than the support temperatures. In theexample of FIG. 8, the support temperatures associated with thecondition number 1 are 10° C. for the first zone, 60° C. for the secondzone, and 30° C. for the third zone. In this mariner, the supporttemperatures can vary in areas from the center to the edge of thesupport.

FIGS. 9A and 9B are diagrams each illustrating exemplary featurecorrection with the etching method according to the second embodiment.In FIG. 9A, a target film 120 and a. mask 130 are formed on a substrate110 in this order. A recess 201 is formed by etching. The recess 201 hasbowing under the interface between the target film 120 and the mask 130.The recess 201 tapers and has a gradually narrower opening downward inthe target film 120. A protective film 301 is formed through the samefilm deposition (step S102 in FIG. 1 as with the etching methodaccording to the first embodiment.

A recess 202 in FIG. 9B expands more in the lateral direction than therecess 201 due to bowing. The lower end of the bowed portion shown inFIG. 9B is slightly lower than the lower end of the bowed portion shownin FIG. 9A. The protective film 301 in the recess 202 in FIG. 9B extendslower than the protective film 301 in the recess 201 in FIG. 9A. Theprotective film 301 is formed at this adjusted position with theadjusted film thickness distribution by setting the temperature of thesupport at the recess 202 differently from the support temperature setat the recess 201. In the examples of FIGS. 9A and 9B. The supporttemperature at the recess 201 is lower than the support temperature atthe recess 202 to form the protective film 301 that extends over thelower end of the bowed portion in each of the recesses 201 and 202. Theprotective film 301 may be formed by chemical vapor deposition (CVD) orunsaturated ALD.

Advantageous Effects of Second Embodiment

The etching method according to the second embodiment above includessteps a), b), c), and d). Step a) includes placing, on a support, asubstrate including a target film, Step b) includes partially etchingthe target film and forming a recess. Step c) includes settingtemperatures of at least two of a plurality of zones of the support todifferent temperatures, and forming, on a sidewall of the recess, thefilm having different film thickness distributions in a depth directionin the at least two of the plurality of zones. Step d) includespartially further etching the target film having the film formed on thetarget film. As described above, controlling the support temperature tovary across the surface of the support allows formation of protectivefilms with appropriate thickness distributions in different areas of thesingle substrate to reduce bowing that may occur at different positionsof the target film in the film thickness direction in such areas duringetching.

Example Structure of Etching Apparatus according to Embodiment

FIG. 10 is a diagram of an exemplary etching apparatus according to oneembodiment. An etching apparatus shown in FIG. 10 is a plasma processingapparatus. A plasma processing apparatus 1 shown in FIG. 10 includes areaction chamber 10, a gas supply unit 20, an RF power supply unit 30,an exhaust system 40, and a controller 50.

In the present embodiment, the reaction chamber 10 includes a support 11and an upper electrode shower head assembly 12. The support 11 islocated in a lower portion of a processing space 10 s within thereaction chamber 10. The upper electrode shower head assembly 12 islocated above the support 11, and serves as a part of a ceiling plate ofthe reaction chamber 10.

The support 11 can support a substrate W in the processing space 10 s.In the present embodiment, the support 11 includes a lower electrode 11,an electrostatic chuck (ESC) 112, and an edge ring 113. The ESC 112 islocated on the lower electrode 111, and can support the substrate W onits upper surface. The edge ring 113 surrounds the substrate W on theupper periphery of the lower electrode. The surface of the support 11that supports the substrate W has multiple zones defined to allowindependent temperature control (refer to FIGS. 7A to 7C). The support11 accommodates multiple heaters. In the example of FIG. 10, threeheaters 111 a, 111 b, and 111 c are arranged radially. Each of theheaters 111 a, 111 b, and 111 c corresponds to one of the zones forheating the corresponding zone. The heaters can have any shapes and canbe of any types. The heaters 111 a, 111 b, and 111 c are respectivelyconnected to temperature controllers 111 d, 111 e, and 111 f.

The upper electrode shower head assembly 12 supplies one or more processgases from the gas supply unit 20 to the processing space 10 s. In thepresent embodiment, the upper electrode shower head assembly 12 includesa gas inlet 12 a, a gas-diffusion compartment 12 b, and multiple gasoutlets 12 c. The gas inlet 12 a allows passage of fluid to and from thegas supply unit 20 and the gas-diffusion compartment 12 b. The gasoutlets 12 c allow communication of fluid with the gas-diffusioncompartment 12 b and the processing space 10 s. In the presentembodiment, the upper electrode shower head assembly 12 supplies one ormore process gases from the gas inlet 12 a through the gas-diffusioncompartment 12 b and the multiple as outlets 12 c into the processingspace 10 s.

The gas supply unit 20 may include one or more gas sources 21 and one ormore flow controllers 22. In the present embodiment, the gas supply unit20 supplies one or more process gases from the respective gas sources 21via the respective flow controllers 22 to the gas inlet 12 a. The flowcontrollers 22 may include a mass flow controller or a pressure-basedflow controller. The gas supply unit 20 may further include one or moreflow rate modulators that supply one or more process gases at amodulated flow rate or in a pulsed manner.

The RF power supply unit 30 provides RE power, or for example, one ormore RF signals, to one or more electrodes, such as the lower electrode111, the upper electrode shower head assembly 12, or both the lowerelectrode 111 and the upper electrode shower head assembly 12. In thepresent embodiment, the RF power supply unit 30 includes two RFgenerators 31 a and 31 b and two matching circuits 32 a and 32 b. The RFpower supply unit 30 in the present embodiment provides a first RFsignal from the first RF generator 31 a via the first matching circuit32 a to the lower electrode 111. An RF spectrum includes a part of anelectromagnetic spectrum in a range of 3 Hz to 3000 GHz. For electronicmaterial processes such as semiconductor processes, an RF spectrum usedto generate plasma may be within a range of 100 kHz to 3 GHz, orspecifically, 200 kHz to 150 MHz. For example, the first RF signal mayhave a frequency of 27 to 100 MHz. The RF power supply unit 30 in thepresent embodiment provides a second RF signal from the second RFgenerator 31 b via the second matching circuit 32 b to the lowerelectrode 111. For example, the second RF signal may have a frequency of400 kHz to 13.56 MHz. In place of the second RF generator 31 b, adirect-current (DC) pulse generator may be used. Although not shown,other embodiments are also possible. For example, in some embodiments,the RF power supply unit 30 may provide the first RF signal from an RFgenerator to the lower electrode 111, the second RF signal from anotherRF generator to the lower electrode 11 1, and a third RF signal fromstill another RF generator to the lower electrode 111. In some otherembodiments, a DC voltage may also be applied to the upper electrodeshower head assembly 12. In various embodiments, the amplitude of one ormore RF signals (such as the first RF signal or the second RF signal)may also be pulsed or modulated. Such amplitude modulation may includepulse-amplitude modulation of an RF signal between an on-state and anoff-state, or between two or more different on-states. Phase matching ofan RF signal may be controlled, and phase matching of amplitudemodulation of two or more RF signals may be or may not be synchronized.

The exhaust system 40 may be connected to an outlet 10 e located at thebottom of the reaction chamber 10. The exhaust system 40 may include apressure valve, a turbomolecular pump, a roughing pump, or a vacuum pumpcombining these.

In the present embodiment, the controller 50 processescomputer-executable instructions that cause the plasma processingapparatus 1 to perform various steps described above. The controller 50may control the components of the plasma processing apparatus 1 toperform various steps described above. The controller 50 may include acomputer 51. The computer 51 may include a central processing unit (CPU)511, a storage 512, and a communication interface 513. The CPU 511 mayperform various control operations in accordance with programs stored inthe storage 512. The storage 512 may include at least one memoryselected from the group consisting of a random-access memory (RAM), aread-only memory (ROM), and auxiliary storage devices including a harddisk drive (HDD) and a solid-state drive (SSD). The communicationinterface 513 may communicate with the plasma processing apparatus 1through a communication line such as a local area network (LAN).

As described above, the apparatus according to the embodiment is anetching apparatus and includes a reaction chamber with a processingspace. The etching apparatus includes a support accommodated in thereaction chamber. The support includes multiple zones for whichtemperatures are independently controllable. The support includes asupport surface onto which a substrate is placeable. The etchingapparatus includes a gas supply unit to supply a process gas into thereaction chamber. The etching apparatus includes a controller to controltemperatures of multiple zones and an operation of the gas supply unit.The controller causes components to perform an etching method. Theetching method includes a) placing, on a support, a substrate includinga target film. The etching method includes b) partially etching thetarget film and forming a recess. The etching method includes c) settingthe temperature of the support at a first temperature, and forming, on asidewall of the recess, a first film having a first film thicknessdistribution. The etching method includes d) partially further etchingthe target film having the first film formed on the target film. Theetching method includes e) setting the temperature of the support at asecond temperature different from the first temperature, and forming onthe sidewall of the recess, a second film having a second film thicknessdistribution different from the first film thickness distribution.

The embodiments described above are mere examples and are not intendedto limit the scope of the present disclosure. Various additions,omissions, substitutions, and changes may be made without departing fromthe spirit of the present disclosure.

REFERENCE SIGNS LIST

-   1 Plasma processing apparatus-   10 Reaction chamber-   10 e Outlet-   10 s Processing space-   11 Support-   111 Lower electrode-   111 a, 111 b, 111 c Heater-   111 d, 111 e, 111 f Temperature controller-   112 Electrostatic chuck (ESC)-   113 Edge ring-   12 Upper electrode shower head assembly-   12 a Gas inlet-   12 b Gas-diffusion compartment-   12 c Gas outlet-   20 Gas supply unit-   21 Gas source-   22 Flow controller-   30 Radio-frequency (RF) power supply unit-   31 a, 31 b First and second RF generator-   32 a, 32 b First and second matching circuit-   40 Exhaust system-   50 Controller-   51 Computer-   511 Central processing unit-   512 Storage-   513 Communication interface-   W Substrate

What is claimed is:
 1. An etching apparatus, comprising: a reactionchamber; a support located within the reaction chamber and configured tosupport a substrate including a target film; a gas supply unitconfigured to introduce process gases to the reaction chamber, theprocess gases including at least one of an etching gas, a precursor, anda reactant; a temperature setting device configured to control atemperature of the support; and a computer-based controller configuredto control a) placement of a substrate on the support; b) the gas supplyunit to introduce a first process gas to the reaction chamber topartially etch the target film and form a recess therein; c) thetemperature setting device to set a temperature of the support at a.first temperature after performing the partial etching; d) the gassupply unit to introduce a second process gas to the reaction chamber toform a first film on a sidewall of the recess, the second process gasbeing different from the first process gas and the first film having afirst film thickness distribution; e) the gas supply unit to introduce athird process gas to the reaction chamber to partially further etch thetarget film after the first film has been formed on the sidewall of therecess, the third process gas being different from the second processgas; f) the temperature setting device to set the temperature of thesupport at a second temperature different from the first temperatureafter the partially further etching; and g) the gas supply unit tointroduce a fourth process gas to the reaction chamber to form a secondfilm on the sidewall of the recess, the fourth process gas beingdifferent from the third process gas and the second film having a secondfilm thickness distribution different from the first film thicknessdistribution.
 2. The etching apparatus according to claim 1, wherein thesupport further comprises a plurality of zones and the controller isfurther configured to control the temperature setting device to adjust atemperature of a first zone of the support corresponding to a first areaof the substrate to a temperature different from a temperature of asecond zone of the support corresponding to a second area of thesubstrate to form the first film in the first area to have at least oneof a thickness or a position different from a thickness and a positionof the first film formed in the second area.
 3. The etching apparatusaccording to claim 2, wherein the first zone includes a center of thesupport, and the second zone includes an edge of the support
 4. Theetching apparatus according to claim 1, further comprising: a pluralityof heaters corresponding to the plurality of zones of the support. 5.The etching apparatus according to claim 2, wherein the controller isconfigured to control the temperature setting device to provideindependent temperature control in each zone of the plurality of zones.6. The etching apparatus according to claim 5, wherein the plurality ofzones is defined concentrically within the support.
 7. The etchingapparatus according to claim 6, wherein one or more of the zones of theplurality of zones comprises multiple zones defined circumferentiallyfrom the center of the support toward the circumference of the support.8. The etching apparatus according to claim 1, wherein the controller isfurther configured to control the temperature setting device to set thesecond temperature to a higher temperature than the first temperature.9. The etching apparatus according to claim 8, wherein the supportfurther comprises a plurality of zones and the controller is furtherconfigured to control the temperature setting device to adjust atemperature of a first zone of the support corresponding to a first areaof the substrate to a temperature different from a temperature of asecond zone of the support corresponding to a second area of thesubstrate to form the first film in the first area to have at least oneof a thickness or a position different from a thickness and a positionof the first film formed in the second area.
 10. The etching apparatusaccording to claim 9, wherein the first zone includes a center of thesupport, and the second zone includes an edge of the support.
 11. Theetching apparatus according to claim 10, wherein d) includes control ofthe gas supply to d-1) supply a first reactant which causes the firstreactant to be adsorbed on the sidewall of the recess, and d-2) supply asecond reactant which causes the second reactant to react with the firstreactant to form the first film, g) includes control of the gas supplyunit to g-1) supply a third reactant and causing the third reactant tobe adsorbed on the sidewall of the recess, and g-2) supply a fourthreactant and causing the fourth reactant to react with the thirdreactant to form the second film, and wherein the controller is furtherconfigured to control a duration of d-2) and a duration of g-2), theduration of g-2) being different from the duration of d-2) so as to formthe first film to have at least one of a thickness or a positiondifferent from a corresponding thickness or position of the second film.12. The etching apparatus according to claim 9, wherein the controlleris configured to provide independent temperature control in each zone ofthe plurality of zones,
 13. The etching apparatus according to claim 12,wherein the plurality of zones is defined concentrically within thesupport.
 14. The etching apparatus according to claim 12, wherein one ormore of the zones comprises multiple zones defined circumferentiallyfrom the center of the support toward the circumference of the support.15. An etching apparatus, comprising: an etching chamber; a supportdisposed within the etching chamber, wherein the support is configuredto support a substrate including a target film; a gas supply unitconfigured to introduce processing gases into the etching chamber togenerate plasma from the processing gases introduced to the etchingchamber first processing gas introduced into the etching chamber fromthe gas supply unit is configured to partially etch the target film andform a recess therein and a temperature controller configured to set thetemperatures of at least two of a plurality of zones of the support todifferent temperatures after performing the partial etch, wherein inresponse to a second processing gas different from the first processinggas introduced into the etching chamber, a film is formed on a sidewallof the recess, the film having different film thickness distributions,in a depth direction, in areas corresponding with the at least two ofthe plurality of zones, and in response to another plasma generated froma third processing gas that is different from the second processing gasintroduced into the chamber by the gas supply unit, further etch thetarget film after the film has been formed on the recess of the targetfilm.
 16. The etching apparatus according to claim 15, wherein a firstzone of the at least two of the plurality of zones includes a center ofthe support, and a second zone of the at least two of the plurality ofzones includes an edge of the support.
 17. The etching apparatusaccording to claim 15, wherein the temperature controller is configuredto provide independent temperature control in each zone of the pluralityof zones.
 18. The etching apparatus according to claim 17, wherein theplurality of zones is defined concentrically within the support.
 19. Theetching apparatus according to claim 17, wherein one or more of thezones of the plurality of zones comprises multiple zones definedcircumferentially from the center of the support toward thecircumference of the support.
 20. An etching apparatus, comprising: areaction chamber; a support located within the reaction chamber andconfigured to support a substrate including a target film; a gas supplyunit configured to introduce process gases to the reaction chamber, theprocess gases including at least one of an etching gas, a precursor, anda reactant; a temperature setting device configured to control atemperature of the support; and means for controlling a) placement of asubstrate on the support; b) the gas supply unit to introduce a firstprocess gas to the reaction chamber to partially etch the target filmand form a recess therein; c) the temperature setting device to set atemperature of the support at a. first temperature after performing thepartial etching; d) the gas supply unit to introduce a second processgas to the reaction chamber to form a first film on a sidewall of therecess, the second process gas being different from the first processgas and the first film having a first film thickness distribution; e)the gas supply unit to introduce a third process gas to the reactionchamber to partially further etch the target film after the first filmhas been formed on the sidewall of the recess, the third process gasbeing different from the second process gas; f) the temperature settingdevice to set the temperature of the support at a second temperaturedifferent from the first temperature after the partially furtheretching; and g) the gas supply unit to introduce a fourth process gas tothe reaction chamber to form a second film on the sidewall of therecess, the fourth process gas being different from the third processgas and the second film having a second film thickness distributiondifferent from the first film thickness distribution.